Electrodeposition of nickel



3,111,466 ELECTRODEPOSITION F NICKEL Donald Gardner Fonlke, Watt-hung, William B. Stoddard, In, Matawan, Otto Kai-dos, Red Bank, and Walter B. Kleiner, l'lainfieid, N.J., assignors to Hansonan Winlde-Munning Company, a corporation of New Jersey No Drawing. Filed Mar. 11, 1959, Ser. No. 798,583 12 Claims. (Cl. 204-49) This invention relates to electroplating and, more particularly, to electrodepositing nickel from an aqueous acidic nickel plating bath. The invention is based on the discovery that certain 1,2-benzopyrones, when incorporated in a nickel plating bath in conjunction with various watermd grate Patent 0 "ice benzopyrone compound in the bath should be maintained at or near its saturation point.

Any 1,2-benzopyrone compound which is capuhli being dissolved by acid and which does not uno composition upon protonation may be ch u ,r clusion in the plating solution, provided tile Ol'll fUlH- not sterically hindered nor impeded its approach to cathode. The compounds listed in Table I are exsrnp of 1,2-benzopyrones which have been used successfully in plating baths containing various water-soluble acctyleuic brighteners. These 1,2-benzopyrone compounds, including coumarin and substituted coumarins, may be used over a very wide range of concentrations, but they are preferably employed in an amount in the range from nlllltgrams per liter to a saturation concentration.

TABLE I 1,2-Benzopyrone Compounds soluble acetylcnic brightening addition agents, are remarkably effective for promoting the formation of ductile electroplates which are much smoother than the base metal plated in such a bath. This ability of an electroplating bath to improve on the smoothness of the basis metal is known as leveling ability and can be used industrially to reduce or eliminate mechanical or electrochemical finishing of the base metal.

We have found that in all instances the combined use of a 1,2-benzopyrone compound and a water-soluble acetylenic compound exerts a synergistic effect on the leveling capacity of the bath as compared with the use of either compound alone. In addition to being notably smoother than the base metal, electrodeposits of nickel formed from a plating bath containing both a 1,2-benzopyrone and an acetylenic brightening addition agent have also been found to be exceptionally resistant to corrosion, even when the electroplate is subjected to the most severe accelerated corrosion tests.

Only relatively small quantities of these 1,2-benzopyrone compounds are required in the plating bath when they are used in conjunction with a water-soluble acetylenic compound, for, in general, concentrations as low as 25 milligrams per liter have been found to promote ett'ective leveling. In many cases, however, at least 50 milligrams per liter of the 1,2-benzopyrone compound should be employed to secure a high leveling etfcct in the bath. To obtain maximum leveling, the concentration of the 1,2-

Coumarin or a substituted coumarin is employed in the plating bath in conjunction with a wate1'soluble ace:- ylenic compound, particularly the oxygen-committing nestylenic compounds. Plating baths which contain count (or a substituted coumarin) together with a WFllL 1"soil acetylenic brightener additive have a much wider bllglltening capacity and more often yield bright and ductile electrodeposits than baths which contain either additive alone. Our experiments indicate that any water-soluble acetylenic compound effectively cooperates to some degree with the 1,2-bcnzopyrone compound for enhancing 1h: leveling, uniformity of brightness, and ductility oi the nickel electroplatc, though some acetylenic compounds are more effective than others.

The common structural feature of these water-salable acetylenic compounds is the presence of a highly nucicophilic triple bond which is neither sterically hindered no: impeded in approaching the cathode. Only relativismall quantities of the acctylenic compounds are required in the plating bath when used in conjunction with a l,2-benzopyrone compound. Concentrations as low as 0.1 iniilimole per liter, or even less, are eilective in some cases though in general it is preferable to employ at lCZlSi millimole per liter. There appears to be no critical upper limit on the concentration of these acetylenic brightcncrs save solubility, but there is no advantage generally in em ploying more than 25 millimroles per liter, and in most plating baths substantially the full benefit of their presence is achieved with concentrations in the range from 1 to 10 millimoles per liter.

A preferred process according to this invention for producing a ductile, corrosion-resistant nickel deposit sub- 5 stanti ally smoother than the basis metal to which it is applied comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved (a) from about 25 milligrams per liter to a saturation concentration of a 1,2-benzopyrone command of the group consisting of coumarin and substituted :oumarins in which at least one of the hydrogen atoms is ;:placed with a substituent selected from the group consisting of alkyl radicals, alkoxy radicals, acyl radicals, and halogen radicals, and (b) from 0.1 to millimoles per liter of a water-soluble acetylenic compound.

While any water-soluble acetylenic compound may be employed in the plating bath conjointly with coumarin or a substituted coumarin to produce corrosion-resistant and ductile nickel deposits in accordance with the invention, particularly satisfactory results have been obtained using tit-substituted acetylenic compounds having a structure represented by the formuia I l i and byalkenyl,

substituin which each of R and R are substitucnts of tin consisting of hydrogen, alkyl, alkenyl, alkynyl, droxy-substituted and alkoxy-substituted allsyl, and alkynyl groups, and each of R, and R, are cuts of the group consisting of hydroxy, alkoxy, carbon-- substituted alkoxy, formoxy, alkanoxy, halogen, and poly-- oxy groups. Where R is a substituted-alkyl group having the above-illustrated structural configuration, then the acetylenic compound is termed an a,a'-disubstituted acetylenic compound, since both carbon atoms vicinal to the. same acetylenic bond contain either the same or a ditferent functional group. The compounds listed in Table ii are examples of various tit-substituted acetylenic compounds which may be used successfully in plating baths containing coumarin or a substituted cournarin. As inuicaten R C:C (J*Rl previously, these acetylenic compounds are preferably r. i used in concentrations from about 1 to about 10 millimoles 1t per liter.

TABLE II tat-Substituted Acetylenic Compounds 2 Rt-CEC-Rr Compound R; R: R; Ita

3-Butyno-l,2-di0l (7Hz0H Il' -II -t)lt 3-Methyl-l-butyn-li-ol -(Hl (Ih li -()li 3-Metl1yl-bpentyn-Iip -CzII --(ll: ll -tlli Z-Propyrrl-ul -11 I[ -11 t) u 2,5Diruell1yl-locten-Lt-yn-5-ol (:H1 Cllz (glls -01! t' CH; 8-Mt-thyl-l-ncnyn-3-nl Hu (i[; ll tJll 2,4-1Icxadlyne-Lfi-diol -11 -11 (E(.-C]I;OII (lll i-lViethoxy-2-propyne H II t) t ll; 3-Mcthoxy-Zt-methyl-4,t'rhnptadiyna- C;Hs -(,Il: *(ZECII (Hill H-Ethew-3,5,7-trin1cLhyl-l'octync -Cil1n Cltt I Mimi l-Formoxy-2-prcpyne II -H l[ --()FII ll U l-Acetoxy-hiropync II II II OCCI[;

B-Mcthyl-l-n0nyn-3-yl acetate CuIIti -Clia -H 0((Il,1

ll U 3-Metbyl-1-butyn-Iryl acetate CII; -CII; -11 -O((".ll

ii 0 l-ChIoro-G-methoxy-Q,4-hexadiync lI -II EC-ClIaOCIi: tl 3-Chloro3-methyl--hwyno. ll' -CII3 (ill -tl 1-Bronto-2-propyno -II -li "llr 1,2-Di-(B-hydroxycthoxy)-3-butyne -CHOCIhCHzOIl -11 lI oCmCll Oit S-(fl-Hydroxy y-chloropl'opoxy)-3-tnethyl-4- C:Us -(ll.\ II till tll pentynu. l

OC1i1CliOII 3-(6.1-Epoxypropoxy)-3-mcthy1-4-pentyne. C2Hs -CII1 ]I 0 ,O("lI:(ll-- (ill;

in which each of R; and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hydroxysubslituted and alkoxy-substituted alkyl,

alkenyl, conjunction with a l,2-bcnzopyronc compound,

Table III sets forth examples of a,a-dist|bstittlteti acct ylenic compounds which, when used in the plating bath in yield 5 nickel electroplates which are exceptionally resistant to corrosion and possess improved ductility.

TABLE III 6 polyethoxy)-2-butyne has been found to be exceptionally pronounced when the bath is operated at temperatures a,a'-Disubstituted Aeetylenic Compounds Among the most satisfactory acetylenic brightening agents are those prepared by reacting either an a-hydroxy or an a,'-dihydroxy acetylenic compound, such as those listed in Tables 11 and III, with either ethylene oxide or epichlorohydrin. These adducts readily dissolve in acidic nickel plating baths, and are unusually effective in such baths both in promoting the formation of bright and duetile electrodeposits over wide current density ranges and in exerting a pronounced leveling effect on the bath during the plating operation. Two such adducts which are notably effective when used in conjunction with the 1,2-benzopyrone compound, particularly with 3-bromocoumarin, are the u,a'-di-(polyoxy)2-butynes obtained upon the reaction of 2-butyne-1,4-diol with ethylene oxide and with epichlorohydrin.

2-butyne-l,4-diol reacts with ethylene oxide in the presence of a base to form a l,4-di-(hydroxypolyethoxy)2- butyne which is structurally characterized by the formula The leveling effect of 3-bromocoumarin used in conjunction with either 2-butyne-1,4-di0l or a 1,4-di-(hydroxyranging from about 50 C. to about 85 C. and at a pli from about 3.0 to 4.5 and when the concentration of 3- bromocoumarin is maintained at or near its saturation point. To maintain the concentration of 3-bromocoumarin at this optimum level in the plating bath, the electrolyte may be circulated continuously through a litter pad consisting of diatomaceous earth mixed with crystalline 3-bromocoumarin. By using this method, it s impossible to supersaturate the plating solution with the bromocoumarin compound no matter at which tcmperzn ture the bath is operated since the maximum soiuhility of 3-bromocoumarin in the electrolyte is that at which substantially maximum leveling is obtained. Moreover, the melting point of 3-bromocoumarin is appreciably higher than the highest temperatures used in most commercial bright nickel plating processes, and consequently there 9; no objectionable introduction of molten compound in o the bath even at the maximum commercial lating temperatures. By using 3-bromocoumarin in the plating solution, it is possible to employ both higher temperatures and higher current densities and to complete the plating opera tion more rapidly than can be done by using any other 1,2-benzopyrone compound in the bath The following examples, which are summariizctl in Tables [V through Vi, are illustrative of the eflcctivcness with which coumarin and substituted couniurins may be used in conjunction with various water-soluble acetylcnic brightening addition agents in accordance with this invention. In each example, the electrodeposit was IQI'ITItti from a Watts plating bath having the following basic com position:

Grams per liter Nickel sulfate, NiSO -7H O 3th) Nickel chloride, NiCl -6H O .a 4:5 Boric acid, H 80 4l.25

Plating operations in each example were carried out in an open vessel on steel and polished stainless steel cathodes. using vigorous air agitation, a bath pH of about 41 a bath temperature of 60 C., and an average current density of 60 ampercs per square foot. The average thickness or each electrodeposit was 0.025 millimeter (0110i inch).

Table IV sets forth the results obtained when nickel was electrodeposited from the standard Watts plating bath which contained varying concentrations of 3-bromocoumarin, alone and in combination with a representative water-soluble aoetylenic compound. In each of the examples summarized in Table IV, the foil ductility of the plated panel was determined by the Chrysler foil ductility test (in which the foil is removed from the plated panel and then bent between the jaws of a micrometer until it cracks, foil ductility being defined as the ratio of the foil "iickncss to the micrometer reading when cracking first r ccurs), the theoretically maximum value being 0.5 for t ctiltnickel electrodeposits. The leveling effect exerted by the bath, which is a measure of the decrease in roughness of the nickel electrodeposit compared to that of the underlying metal surface, was also determined in each of these examples by measuring the surface roughness (root mean square value in microinches) of the steel panel with a brush surface analyzer prior to the plating operation and then immediately following the plating operation.

TABLE IV Cumulative Eflccl of 3-Bromocoumarin and Various Acctylem'r Compounds n the Leveling and Ductillty of Nickel Elcctrodcposrts Character of 3-Bromn- Electrodepostt Aretylenic Compound Cone, cougnLll. rnnrin,

rug/l. Leveling, Due I)-L percent tillty Factor None (1.0 50 68 (l. 34. 0 2-Butyne-l,4-dloi (1. ll) t). 0 ill. 6 0.0 (l. 0 0 Q!) 75 0. 5 3T. 5 0 it] 123 83 0. 5 4t. 5 l). 112 5S 7L 9 (l. 5 35. 95 3-Meth }'l-l-l)l1lyIt-3-Ol... U. 05 so 73 (l. 5 36. 5 l-iiromo-Ll-propync (1,05 80 77. 5 0. 5 38. 75 1,4-l)l-(B-hydroxyctlmxy)-2butyue 0. 106 St) 75 0. 5 37. 5 3-Mothyldbutmml-yne U. 090 50 7O 0. 5 35.0 1,4-Dlchloro-2-butyne t]. 100 82 0.5 41. 0 Itropiolte acid (J. 30 81 t). 5 40. 5

TABLE V Effect of Coumarin and Various Acetylenic Compounds 0n the Ducfility and Leveling of Nickel Electrodeposits Character of Gcti- Eleetrodtposit Acetylenlc Compound Cone, marin, gmJ]. mgJl.

Leveling, Duc- D-L percent ttllty Factor None 0. 0 s0 60 0.5 30.0 Z-ButyneJA-diol 0.1 0.0 50. 6 0 U U. 15 s0 80. 5 l). 5 43. 1 -l-Dl-(fl-hydroxyr 2: 1-1.. it 2;; at l-llromo-i rpropynn 0. 15 5t] 05 D. 5 32. 5 1,-t-Dit-h loro-Z-butyne. 0. 05 Q0 65 0.5 32. 5

The general principle illustrated in Tables IV and V, that coumarin or substituted eoumarins are capable of functioning as carrier" brighteners when used in a nickel plating bath in conjunction with a water-soluble aeetylenic brightener, was repeatedly and consistently verified in another series of tests using a variety of acetylenie brighteners, including many representative alkynolepoxide adduct's. Although the basis or reaction mechanism by which these l,2-ben2opyrone compounds function in a nickel plating bath in combination with acetylenic brighteners is not completely understood, it is apparent from the examples summarized in Tables 1V and V that the plating bath must contain both the 1,2- benzopyrone compound and the acetylcnic brightener to obtain both the maximum ductility together with leveling. the criterion of which is indicated by a high D -L factor which, in turn, is defined as the product or the mi ductility times the leveling. Moreover. eiwctrodeym of nickel formed from a bath containing both the L2 benzopyrone compound and an acetylenic brighteucr possess an exceptionally notable resistance to corrosion. even when subjected to the most severe accelerated corrosion tests.

To illustrate the improved corrosion resistance exhibited by electrodcposits formed from plating baths containing a 1,2-benzopyrone compound and a watersoluble acetylenic brightener in accordance with the in vention, Table VI lists the corrosion ratings of tour duplex-plated panels produced from the basic Watts plating bath which contained an acetylenic compound together with either a 1,2-benzopyrone compound (3- bromocoumarin or coumarin) or a sulfo-oxygcn carrier addition agent (sodium naphthalene-l,3,6-trisulfonate). As before, plating operations were carried out in an open vessel on steel panels, using substantially the same conditions as previously described, each panel receiving a duplex coating having an average thickness of 1.5 mils. Each of the plated panels was coated with a synthetic soil consisting of a paste prepared by persing 0.035 gram of cupric nitrate, 0.l65 grain of tar ric chloride, 1.0 gram of ammonium chloride, and 30.0 grams of kaolin in 50.0 milliliters of distilled water. After each panel had been uniformly coated with a layer of the synthetic soil, the coated panel was exposed. to a constant humidity of about percent at a tempera ture of F. for a period of 24 hours, following which the synthetic soil was removed by washing and the panel then immersed in boiling water for an additional a hours. The relative corrosion resistance of each etc-stroplate is expressed in terms of its Corrodekote ramrg which was determined by the oflicial Corrodekote test of the American Electroplaters Society. This rating is graded on a logarithmic scale from zero [negligible corrosion resistance) to 10 (complete corrosion resistance), values above 9.0 representing exceptionally high resistance to corrosion.

TABLEVI Relative Corrosion Resistance of Nickel Elcclrodeposits Bath 1 Built 2 Bath 3 Bath 4 butyno (gin/1.)" Coumarln (mg/LL 3-Bmmocoumarin (mg l1 Sodium nnph thulencl,3,l'i-

trlsuttonate (gin/l.)

B. Corrodekoto Rating or Elcctrui deposit. (Scale=0-10J 914 D. 7 9.

baths. For example, these l,2-benzopyrone compounds are beneficial when used in straight nickel sulfate baths, in nickel sulfate-chloride baths, and in various other nickel plating baths based on using nickel sulfamate or nickel fluoborate as the nickel salt which is dissolved in an aqueous acidic solvent, and consequently the invention is applicable to electroplating from any aqueous acidic solution of one or more nickel salts.

We claim:

I. A process for producing a corrosionresistant nickel deposit substantially smoother than the basis metal to which it is applied which comprises electrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved (a) from about 25 milligrams per liter to a saturation concentration of a l,2-bcnzopyrone compound of the group consisting of coumarin and substituted coumarins in which at least one of the hydrogen atoms is replaced with a substituent selected from the group consisting of alkyl radicals, alkoxy radicals, acyl radicals, and halogen radicals, and (b) from 0.1 to 10 millimoles per liter of a watersoluble acctylenic compound.

2. A process for producing a corrosion-resistant nickel deposit substantially smoother than the basis metal to which it is applied which comprises electrodepositing nickcl from an aqueous acidic solution of at least one nickel salt in which there is dissolved (at) from about 25 milligrams per liter to a saturation concentration of a 1,2-bcnzopyronc compound of the group consisting of coumarin and substituted coumarins in which at least one of the hydrogen atoms is replaced with a substituent selected from the group consisting of alkyl radicals, alkoxy radicals, acyl radicals, and halogen radicals, and (b) from 0.1 to it) millimoles per liter of an int-substituted acetylenic compound having a structure represented by the formula R1 R:CEC-(IJR1 it in which each of R, and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hydroxy-substituted and alkoxy-substituted alkyl, alkenyl, and alkynyl groups, R is a substituent of the group consisting of hydrogen, halogen, alkyl, alkcnyl, alkynyl, hydroxy-substituted and alkoxy-substituted alkenyl and alkynyl groups, and substituted-alkyl groups having the structural configuration Rt; R.5( J l.. in which each of R and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hydroxy-substituted and alkoxy-substituted alkyl, alkenyl, and alkynyl groups, and each R, and R,,- are substituents of the group consisting of hydroxy, alkoxy, carboxy-substitutcd alkoxy, formoxy, alkanoxy, halogen, and polyoxy groups.

3. A process for producing a corrosion-resistant nickel deposit substantially smoother than the basis metal to which it is applied which comprises elcctrodepositing nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved (at) from about 25 milligrams per liter to a saturation concentration of a l,2-bcnzopyrone compound of the group consisting of coumarin and substituted coumarins in which at least one of the hydrogen atoms is replaced with a substituent selected from the group consisting of alkyl radicals, alkoxy radicals, acyl radicals, and halogen radicals, and (/7) from 0.1 to 10 millimoles per liter of an a,a-disubstitulcd acetylenic compound having a structure represented by the formula l (a its in which each of R R R and R are substitucnts at the group consisting of hydrogen, alkyl, alkenyl, alltynyi, and hydroxy-substituted and alkoxy-substituted alkyl, alkenyl, and alkynyl groups, and each of R,, and it are substituents of the group consisting of hydroxy, alkoxy, carboxy-substituted alkoxy, formoxy, alkanoxy, halogen, and polyoxy groups.

4. A process for producing a corrosion-resistant nickel deposit substantially smoother than the basis metal l which it is applied which comprises elcctrodcpusttni nickel from an aqueous acidic solution of at lea w nickel salt in which there is dissolved {u} from milligrams per liter to a saturation concentration til 1,2-benzopyrone compound of the group consisting i coumarin and substituted coumarins in which at Jew-Ll one of the hydrogen atoms is replaced with a StllJstitUcfi. selected from the group consisting of alkyl radicals, ;rlkoxy radicals, acyl radicals, and halogen radicals, and (b) from 1 to 10 millimoles per liter of a W1lCl-ROltt tlJ acetylenic compound selected from the group consis of 2 propyn I ol, Lbromo-Z-propyne, 1,4dicl1lorr butyne, 2-butyne-l,4-diol, 3-methyl1-butyn-3-ol, tt-pt oxy acetylenic compounds having a structure rcprcscntc by the formula and a,a'-di(polyoxy) acetylenic compounds having structure repesented by the formula in which each of R R R and R are substituents at the group consisting of hydrogen. alkyl, alkenyl. alkynyl. and hydroxy-substituted and alkoxy-substitutcd alltyl, alkenyl, and alkynyl groups, R is a suhstitucnt ol' the group consisting of hydrogen. halogen. alkyl, alkcnyl. ulkynyl, hydroxy-substituted and alkoxy-suhstitutcd alkenyt and alkynyl groups, and substituted-alkyl groups havnu, the structural configuration t not la.

in which R, is a suhstitucnt of the group consisting hdroxy, alkoxy, carboxy-substitutcd alkoi-cy, alkanoxy, halogen, and polyoxy groups, and n is an integer from 1 to 20.

5. A nickel electroplating bath for producing a cor rosion-resistant nickel deposit substantially s nusitis-r than the basis metal to which it is applied comprising an aqueous acidic solution of at least one nickel salt in which; there is dissolved from about 25 milligrams per liter to a saturation concentration of 3-bromocoumarin, and in; at 0.1 to 10 millimolcs per liter of a water-soluble acctylerlc compound.

6. A nickel electroplating bath for producing a curry sion-resistant nickel deposit substantially smooluur than the basis metal to which it is applied minimisin an aqueous acidic solution of at least one nickel salt llll which there is dissolved from about 25 milligrams per ll;.r a saturation concentration of 3bromocoumnrin, and iron; 0.1 to 10 millimoles per liter of an a substitutcd acetylcnic compound having a structure represented by the :ornmiu droxy-substituted and alkoxy-suhstitutcd alkyi, alkcnyl. and alkynyl groups. and R is a substituent of the gruuzi consisting of hydrogen, halogen, alkyl, anltciiyi, ulkyngu,

I 1 hydroxysubstituted and alkoxy-substituted alkenyl and alkynyl groups, and substituted-alkyl groups having the structural configuration in which each of R and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and bydroxy-substituted and alkoxy-substituted alkyl, alkenyl, and alkynyl groups. and each of R,, and R, are sub- :titucnts of the group consisting of hydroxy, alkoxy, caruoxy-substituted alkoxy, formoxy, alkanoxy, halogen, and polyoxy groups.

7 A nickel electroplating bath for producing a corrosion-resistant nickel deposit substantially smoother than the basis metal to which it is applied comprising an aqueous acidic solution of at least one nickel salt in which there is dissolved from about milligrams per liter to a saturation concentration of 3-bromocoumarin, and from 0.1 to it) millimoles per liter of an a,a-disubstituted ac/etylcnic compound having a structure represented by the formula in which each of R R R and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and hydroxy-substituted and alkoxy-substituted alkyl, alkenyl, and alkynyl groups, and each of R, and R, are substituents of the group consisting of hydroxy, alkoxy, carboxy-substituted alkoxy', formoxy, alkanoxy, halogen, and polyoxy groups.

8. A nickel electroplating bath for producing a corrosion-resistant nickel deposit substantially smoother than the basis metal to which it is applied comprising an aque ous acidic solution of at least one nickel salt in which there is dissolved from about 25 milligrams per liter to a saturation concentration of 3-bromocoumarin, and from 1 to 10 millimoles per liter of a water-soluble acetylenic compound selected from the group consisting of Z-propyn l-ol. l-bromo-2-propyne, l,4-dichloro-lhutyne, 2-butyne 1,4-diol, 3methyl-l-hutyn-3-ol, m-polyoxy acetylenic compounds having a structure represented by the formula R1 R;--CC-0-[Cllz UlhOLr-II 1 11 and a,a'-di(polyoxy) acetylenic compounds having a structure represented by the formula in which each of R R R and R are substituents of the group consisting of hydrogen, alkyl, alkenyl, alkynyl, and

hydroxy-substituted and alkoxy-suhstituted ulkyl, alkengl. and alkynyl groups, R is a substituent of the group CUll" sisting of hydrogen, halogen, alkyl, alkenyl, alkynyl, h droxy-substituted and alkoxy-suhstituted ulkenyl and ul kynyl groups, and substituted-alkyd groups having the structural configuration in which R,,- is a suhstitucnt of the grou Linil l r,, hydroxy, alkoxy, carboxy-substituted aikoir, hunt. alkanoxy, halogen, and polyoxy groups, and n is an illlL li from 1 to 20.

9. A process for producing a corrosion-resistant nickel deposit substantially smoother than the basis metal in which it is applied which comprises clectrodeposilin i nickel from an aqueous acidic solution of at least one nickel salt in which there is dissolved from about 2?? milli grams per liter to a saturation concentration of -bromn coumarin, and from 0.05 to /3 gram per liter of Zhutynm 1,4-diol.

10. A process for producing a corrosion-resistant nickel deposit substantially smoother than the lttlsis ntclul in which it is applied which comprises electrodeposit it nickel from an aqueous acidic solution of at least ill. nickel Salt in which there is dissolved from about 25 milli grams per liter to a saturation concentration of .l-hronu coumarin, and from 1 to It) millimolcs per liter ol' Cl watt soluble a,a'-di(polyoxyl-2-butyne having ct structure rep resented by the formula O-lCii CH Ol,,-ll in which n is an integer from I to 20.

11. A process for producing a corroslon rcsistunt nickel deposit substantially smoother than the basis metal to which it is applied which comprises clectrntlepnsiting nickel from an aqueous acidic solution of at least one nickel salt at a temperature from about 50 f. to about C. and at a pH between 3.0 and 4.5 and in which lhuc is dissolved from 0.05 to 1 gram per liter of n crsoluble acetylenic compound while maintaining a s:t':lr;ttion concentration of B-bromocoumarin in the solution.

12. A process for producing corrosion-resistant nickel deposit which comprises electrodepositing nickel from ill. aqueous acidic solution of at least one nickel salt in which there is dissolved from about 0.2 to 3 grams per liter ol coumarin, and from about 0.01 to 1.5 grams per l ter o l a compound selected from the group consisting of l enic alcohols, acetylenic esters and acetylenic cthcrs.

cu l- Du Rose Apr. i4, Kardos ct a]. W July 5, 1%

UN I IED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent. No. 3, 111,466 November l9 1963 Donald Gardner Foulke et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, Table 1, column 6, line 8 thereof, for

3 "--OCH read OCH column 1O line 75, for "ankenyl" alkenyl Signed and sealed this 28th day of April 1964.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A PROCESS FOR PRODUCING A CORROSION-RESISTANT NICKEL DEPOSIT SUBSTANTIALLY SMOOTHER THAN THE BASIS METAL TO WHICH IT IS APPLIED WHICH COMPRISES ELECTRODEPOSITING NICKEL FROM AN AQUEOUS ACIDIC SOLUTION OF AT LEAST ONE NICKEL SALT IN WHICH THERE IS DISSOLVED (A) FROM ABOUT 25 MILLIGRAMS PER LITER TO A SATURATION CONCENTRATION OF A 1,2-BENZOPYRONE COMPOUND OF THE GROUP CONSISTING OF COUMARIN AND SUBSTITUTED COUMARINS IN WHICH AAT LEAST ONE OF THE HYDROGEN ATOMS IS REPLACED WITH A SUBSTITUENT SELECTED FROM THE GROUP CONSISTING OF ALKYL RADIALS, ALKOXY RADICALS, ACYL RADICALS, AND HALOGEN RADICALS, AND (B) FROM 0.1 TO 10 MILLIMOLES PER LITER OF A WATERSOLUBLE ACETYLENIC COMPOUND. 